US20020166807A1 - Underdrain filtration system with stamped perforations - Google Patents
Underdrain filtration system with stamped perforations Download PDFInfo
- Publication number
- US20020166807A1 US20020166807A1 US10/185,638 US18563802A US2002166807A1 US 20020166807 A1 US20020166807 A1 US 20020166807A1 US 18563802 A US18563802 A US 18563802A US 2002166807 A1 US2002166807 A1 US 2002166807A1
- Authority
- US
- United States
- Prior art keywords
- underdrain
- slits
- metal
- discs
- raised
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D24/00—Filters comprising loose filtering material, i.e. filtering material without any binder between the individual particles or fibres thereof
- B01D24/02—Filters comprising loose filtering material, i.e. filtering material without any binder between the individual particles or fibres thereof with the filter bed stationary during the filtration
- B01D24/20—Filters comprising loose filtering material, i.e. filtering material without any binder between the individual particles or fibres thereof with the filter bed stationary during the filtration the filtering material being provided in an open container
- B01D24/24—Downward filtration, the container having distribution or collection headers or pervious conduits
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D24/00—Filters comprising loose filtering material, i.e. filtering material without any binder between the individual particles or fibres thereof
- B01D24/46—Regenerating the filtering material in the filter
- B01D24/4631—Counter-current flushing, e.g. by air
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T29/00—Metal working
- Y10T29/49—Method of mechanical manufacture
- Y10T29/496—Multiperforated metal article making
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T29/00—Metal working
- Y10T29/49—Method of mechanical manufacture
- Y10T29/496—Multiperforated metal article making
- Y10T29/49604—Filter
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T29/00—Metal working
- Y10T29/49—Method of mechanical manufacture
- Y10T29/49826—Assembling or joining
Definitions
- This invention concerns underdrain filtration systems for water purification or sewage treatment systems which employ a filtering medium of stacked granular material retained above a tank floor by perforated metal underdrain structures. More particularly, the invention is concerned with an improvement whereby the perforations in the metal underdrain structures supporting the granular material are formed in an efficient manner so as to establish a high rate of consistency among the opening sizes, as well as promoting a better fluid flow pattern during backflushing.
- the subject high rate gravity filters usually have filter beds with gravel of varying sizes. Liquid from the tank or vessel flows downwardly by gravity through the filter medium and exits the filtration tank through openings in the underdrain structures that support the granular filtration medium. Typically the coarsest gravel of the medium is at the bottom, against the underdrain structure, with the gravel decreasing in size up to the finest gravel or sand, located at the top of the filter bed. Some filter beds are all sand, and the bed may be covered with finely granulated anthracite coal or other types of filter material.
- Backwashing and air scouring are important aspects of these types of gravity filters, for cleaning the filters against clogging.
- Water or a combination of air (or gas) and water is passed up through the filter bed, in the opposite direction of normal filtration.
- Air may be from a tube adjacent to the underdrain structures. Uniform distribution of the backwashing fluids is a goal of most underdrain structures. This includes the systems described in the above-referenced patents, as well as some of the underdrain systems of the following patents: U.S. Pat. Nos.
- Application Ser. No. 09/170,870, U.S. Pat. No. 6,090,284 shows an embodiment of an underdrain structure wherein the water-passing perforations are in the form of narrow slits, small enough to support a bed of sand without allowing the sand to pass through the openings.
- Slit openings were made by laser cutting, as opposed to an earlier practice of forming the openings as ⁇ fraction (3/16) ⁇ ′′ diameter holes, over which gravel was placed.
- the consistency of the opening sizes is important for proper water distribution in backflushing and balancing of pressure drop across the entire underdrain structure.
- Laser cutting is fairly expensive and has typically not been capable of providing a highly consistent range of opening width.
- the openings formed by laser cuts in the experience of the applicant ranged from about 0.008′′ to 0.012′′, a variation of 0.002′′ in both directions from the target size of 0.010′′.
- the resulting differences in pressure drop tended to cause inefficiency in the action of the backwashing water in cleaning the surrounding filter medium.
- the slots would not provide an optimum pattern of pressurized backwash water flow for filter cleaning, as does the system of the invention described below.
- the invention is an improvement in the fabrication and performance of the filter media-retaining underdrain.
- the invention utilizes a machine punch process to produce fine openings in a metal plate of specific thickness gauge, resulting in openings of a very consistent width.
- the openings are 0.010′′ in width and sufficiently small and consistent to directly retain a filter medium (sand) ranging from 0.3 mm to 0.5 mm.
- the punched plate preferably is then folded into a trapezoidal shape such as shown in the above-referenced U.S. Pat. Nos. 4,331,542 and 6,090,284.
- the trapezoidal underdrain structure defines a conduit for carrying filtered water or wash water in a municipal water treatment filter or tertiary treatment in a municipal waste water treatment filter.
- the stampings preferably are circular in shape, although they could be other curved shapes or polygonal, and produce a plurality of slots which lie generally in a circuit defined by the space between a raised disc and the surrounding flat area of the underdrain material.
- the raised discs are circular, with two to four bridges between ends of adjacent slits, these metal bridges being left remaining from the stamping of the discs. Two such bridges between two arcuate slots are generally sufficient, but three bridges will provide more stability of the aperture sizes in the event of rough handling or other forces experienced during transportation, installation and use.
- underdrain structures can support the sand filter medium directly on the underdrain plates, thus eliminating the space normally required for progressively smaller gravel layers positioned over the underdrain to support the sand above, as in previous implementations.
- a further benefit of the stamped-disc orifices is that the raised discs during backflushing through the underdrain create an outwardly diverging water flow pattern beneficial in clearing trapped particles from the filter medium in the vicinity of the underdrain apertures.
- FIG. 1 is a perspective view showing a granular filtration system including an underdrain structure of the type to which this invention relates.
- FIG. 2 is a view showing a flat metal plate punched or stamped to form raised discs and defining of slit openings in the plate, in accordance with the invention.
- FIG. 3 is a perspective view showing a raised disc and resulting slit openings in greater detail.
- FIG. 4 is a view similar to FIG. 2, showing a variation.
- FIG. 5 is a perspective view showing an underdrain structure formed by bending a punched plate such as shown in FIG. 2.
- FIGS. 6A to 6 E are views showing other shapes which can be employed in the punching of the discs to form the slit apertures.
- FIG. 7 is a schematic elevation view showing a plate used over an existing underdrain system to provide advantages of the invention.
- FIG. 1 shows in perspective major components of a liquid filtration system 10 partially in accordance with prior art and also in accordance with features of the invention to be described below.
- the filtration system is formed as part of a tank typically of concrete and having a floor 12 .
- This is a system of the type described in U.S. Pat. No. 4,331,542, as well as some of the other patents referenced above.
- the filtration system as described above and also in the '542 patent, has a bed of granular material 14 which may be topped with a layer of bituminous material 16 .
- a perforated surface 18 at the bottom of the tank preferably a corrugated surface as shown and as described in the '542 patent.
- Such a surface preferably is formed of a series of perforated longitudinal ribs 20 which form triangular or trapezoidal cross-sectional shapes when placed against the floor 12 .
- each perforated longitudinal rib 20 preferably has a horizontal flange 22 at left and right extremities, these flanges of adjacent longitudinal ribs being slightly spaced apart in the completed underdrain unit 24 , thus defining troughs of the corrugations which are partly constituted by the tank floor 12 itself.
- the longitudinal ribs define inner spaces or chambers 26 which collect liquid filtrate passing through the granular bed 14 and through the multiplicity of perforations 28 in the ribs. This filtrate travels to and collects in a gutter or gullet 30 of the tank bottom.
- FIG. 5 shows a form of air scour subsystem wherein air is distributed through a tubular structural member 30 which has air distribution outlet holes or slits shown at 32 .
- This tubular structural member 30 also serves to retain the underdrain structures 20 down against the tank floor 35 , thus serving a dual purpose, as disclosed in the above referenced application Ser. No. 09/170,870, U.S. Pat. No. 6,090,284.
- FIG. 2 shows in flat plan view a sheet of metal 38 , preferably stainless steel in a thickness of about 1.6 mm or slightly under ⁇ fraction (1/16) ⁇ ′′, from which the perforations or apertures 28 are formed in accordance with the invention.
- FIGS. 2 and 3 show that in one embodiment, the apertures are formed by a stamping process, as by a punch press which stamps or punches out raised discs 40 from the flat sheet of material 38 .
- the raised discs 40 formed in accordance with this embodiment are generally circular, with diameters which may be approximately 3 ⁇ 8′′ to 1′′.
- the discs are punched to a controlled depth which opens slits 42 between the disc and the surrounding flat field of metal, and these slits are highly consistent in width.
- a preferred width for this embodiment is about 0.010′′.
- the discs 40 are stably and rigidly retained on the flat metal sheet 38 by metal bridges 44 which are left remaining in the stamping process.
- the stamping die is shaped so as to leave these metal bridges 44 and is precisely formed to result in highly consistently-sized slits 42 serving as perforations for passage of filtrate.
- the granular material 14 can have sand piled directly on the underdrain structure formed from the sheet metal plate 38 , and an intermediate bed of gravel in gradation of sizes can be eliminated. This can save up to about one foot of space in some types of filtration systems.
- the metal stamping a portion of which is shown in FIG. 2, is formed into an underdrain structure which preferably is trapezoidally shaped as shown in FIG. 5.
- the bending of the stamped metal, along bend lines 46 and 48 is done subsequent to the stamping of the apertures, in a preferred implementation of the method, since the stampings are more easily accomplished on a conventional press when the metal piece is in completely flat form.
- a special stamping die could be provided to punch the discs after bending of the plate.
- FIGS. 2 and 3 show stampings which form raised discs 40 connected by two opposed metal bridges 44 .
- these bridges can be greater in number, such as three or four around a circuit of slits, so as to assure a more secure, rigid and stable connection between the raised discs and the surrounding flat metal area.
- three equally spaced bridges are left remaining from the stamping process, thus providing three arcuate slits which are spaced apart 120° and which are separated by the bridges.
- FIG. 4 shows an embodiment wherein raised discs 40 are retained to the surrounding metal plate 38 with four such metal bridges 44 .
- four arcuate slits or punched slots 42 are formed as filtrate apertures, separated by the bridges 44 .
- three such bridges are generally sufficient.
- FIGS. 2, 3 and 4 show aperture slits 42 in a circular pattern, with circular raised discs 40 formed in the stamping process, the circuit of slits and the shape of the disc need not be circular. It is sufficient that the slits be arranged in some form of circuit, the slits being separated by bridges, such that a raised disc of any practical shape is formed in the punching or stamping operation.
- a circle is an efficient shape, but FIGS. 6 A- 6 E shows other shapes, as examples, which can be employed.
- FIG. 6A shows schematically a series of six slits 42 a in a hexagonal pattern, with bridges 44 a between adjacent slits. Thus, a hexagonal raised disc 40 a is formed.
- FIG. 6B shows a square raised disc 40 b , with a pattern of four slits 42 b in a square arrangement, and this could be a non-square, rectangular arrangement.
- FIGS. 6C, 6D and 6 E show other shapes, including a triangular raised disc 40 c , with three slits 42 c in a triangular pattern; an octagonal arrangement in FIG. 6D, with an octagonal raised disc 40 d ; and an oval or elliptical shape in FIG. 6E, with a pair of slit apertures 42 e defined between the surrounding flat metal and a raised oval disc 40 e . Only two slits 42 e are shown at FIG. 6E, but there could be three or four slits.
- FIG. 7 shows schematically another application for the punched slot openings formed in accordance with the invention.
- the drawing shows existing underdrain structures 20 a as implemented prior to the invention, and these typically have ⁇ fraction (3/16) ⁇ ′′ diameter holes for the filtrate. As noted above, these require a support gravel system above the underdrain structure, for supporting the fine granule filter medium such as sand.
- These existing underdrain systems can be fitted with a flat plate 52 placed across the tops of and supported by the flat top portions 20 b of the existing underdrain plates or structures 20 a . This eliminates the need for a support gravel bed above the underdrain structures, increasing the vertical height available for the actual filter medium by about 12 ′′, and thus improving the filtering capability of the existing filter.
- the plate 52 has punched openings as described above (not shown in FIG. 7). By leaving the existing underdrain structure 20 a in place, the illustrated arrangement makes this filter improvement very inexpensive.
- the flat plates 52 can be attached to side walls 54 of the filter system via an angled bend 55 in the plate, with stainless steel anchors 56 as shown, and attached to the tops of the existing underdrain structures 20 a with stainless steel machine screws indicated at 58 . Other methods of securing can be used. Filter sand or anthracite can be placed directly on top of the flat plates 52 with their very fine, preferably 0.010′′ punched openings. Because the plates 52 lie flat, they need to be somewhat thicker than the folded plates forming the underdrain structures 20 described above, in order to support the filter medium and withstand the forces generated by a high rate backwash without permanent deforming.
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Filtering Materials (AREA)
- Filtration Of Liquid (AREA)
Abstract
Description
- This invention concerns underdrain filtration systems for water purification or sewage treatment systems which employ a filtering medium of stacked granular material retained above a tank floor by perforated metal underdrain structures. More particularly, the invention is concerned with an improvement whereby the perforations in the metal underdrain structures supporting the granular material are formed in an efficient manner so as to establish a high rate of consistency among the opening sizes, as well as promoting a better fluid flow pattern during backflushing.
- An example of an underdrain filtration system is shown in application Ser. No. 09/170,870, U.S. Pat. No. 6,090,284. As pointed out in that application and patent, such granular filtration systems typically have corrugated or undulating-shaped perforated underdrain structures, and the systems are equipped to backwash the granular material covering the underdrain units by water, and usually by air from an adjacent source. The assignee's U.S. Pat. No. 4,331,542 also describes an underdrain structure for use with such gravity-fed granular filtration systems, fitted with water backflushing and air scouring.
- As explained in those patents, the subject high rate gravity filters usually have filter beds with gravel of varying sizes. Liquid from the tank or vessel flows downwardly by gravity through the filter medium and exits the filtration tank through openings in the underdrain structures that support the granular filtration medium. Typically the coarsest gravel of the medium is at the bottom, against the underdrain structure, with the gravel decreasing in size up to the finest gravel or sand, located at the top of the filter bed. Some filter beds are all sand, and the bed may be covered with finely granulated anthracite coal or other types of filter material.
- Backwashing and air scouring are important aspects of these types of gravity filters, for cleaning the filters against clogging. Water or a combination of air (or gas) and water is passed up through the filter bed, in the opposite direction of normal filtration. Air may be from a tube adjacent to the underdrain structures. Uniform distribution of the backwashing fluids is a goal of most underdrain structures. This includes the systems described in the above-referenced patents, as well as some of the underdrain systems of the following patents: U.S. Pat. Nos. 4,659,462, 4,707,257, 5,015,383, 5,019,259, 5,156,738, 5,160,614, 5,269,920, 5,332,497, 5,462,664, 5,489,388, 5,512,174, 5,639,384.
- Application Ser. No. 09/170,870, U.S. Pat. No. 6,090,284, shows an embodiment of an underdrain structure wherein the water-passing perforations are in the form of narrow slits, small enough to support a bed of sand without allowing the sand to pass through the openings. Slit openings were made by laser cutting, as opposed to an earlier practice of forming the openings as {fraction (3/16)}″ diameter holes, over which gravel was placed.
- The consistency of the opening sizes is important for proper water distribution in backflushing and balancing of pressure drop across the entire underdrain structure. Laser cutting is fairly expensive and has typically not been capable of providing a highly consistent range of opening width. The openings formed by laser cuts in the experience of the applicant ranged from about 0.008″ to 0.012″, a variation of 0.002″ in both directions from the target size of 0.010″. The resulting differences in pressure drop tended to cause inefficiency in the action of the backwashing water in cleaning the surrounding filter medium. Moreover, even if these slots could be formed perfectly at the target width, the slots would not provide an optimum pattern of pressurized backwash water flow for filter cleaning, as does the system of the invention described below.
- The invention is an improvement in the fabrication and performance of the filter media-retaining underdrain. Instead of round holes or laser-cut slots, the invention utilizes a machine punch process to produce fine openings in a metal plate of specific thickness gauge, resulting in openings of a very consistent width. In one embodiment the openings are 0.010″ in width and sufficiently small and consistent to directly retain a filter medium (sand) ranging from 0.3 mm to 0.5 mm. The punched plate preferably is then folded into a trapezoidal shape such as shown in the above-referenced U.S. Pat. Nos. 4,331,542 and 6,090,284. The trapezoidal underdrain structure defines a conduit for carrying filtered water or wash water in a municipal water treatment filter or tertiary treatment in a municipal waste water treatment filter.
- The stampings preferably are circular in shape, although they could be other curved shapes or polygonal, and produce a plurality of slots which lie generally in a circuit defined by the space between a raised disc and the surrounding flat area of the underdrain material. In one preferred embodiment the raised discs are circular, with two to four bridges between ends of adjacent slits, these metal bridges being left remaining from the stamping of the discs. Two such bridges between two arcuate slots are generally sufficient, but three bridges will provide more stability of the aperture sizes in the event of rough handling or other forces experienced during transportation, installation and use.
- A very highly consistent slit width can be formed in this way, varying less than 0.001″ in either direction, and thereby improving consistency of pressure drop throughout the underdrain. As a result of the small and consistent dimensions achievable with the process of the invention, underdrain structures can support the sand filter medium directly on the underdrain plates, thus eliminating the space normally required for progressively smaller gravel layers positioned over the underdrain to support the sand above, as in previous implementations.
- A further benefit of the stamped-disc orifices is that the raised discs during backflushing through the underdrain create an outwardly diverging water flow pattern beneficial in clearing trapped particles from the filter medium in the vicinity of the underdrain apertures.
- Tests were performed on underdrain sections formed according to the invention were tested for pressure loss. The pressure loss was found to be much lower than head loss through underdrain structures with laser-cut slots of the same total area of openings. This is due to the consistency of the openings and the lack of irregularity along the edges of the slots which are encountered with laser-cut slots.
- It is thus among the objects of the invention to improve the structure, manufacturing procedure and cost of metal underdrains for granular filter beds, through use of a stamping process that forms raised discs in the metal structure, defining slits arranged generally in a circuit. These and other objects, advantages and features of the invention will be apparent from the following description of a preferred embodiment, considered along with the accompanying drawings.
- FIG. 1 is a perspective view showing a granular filtration system including an underdrain structure of the type to which this invention relates.
- FIG. 2 is a view showing a flat metal plate punched or stamped to form raised discs and defining of slit openings in the plate, in accordance with the invention.
- FIG. 3 is a perspective view showing a raised disc and resulting slit openings in greater detail.
- FIG. 4 is a view similar to FIG. 2, showing a variation.
- FIG. 5 is a perspective view showing an underdrain structure formed by bending a punched plate such as shown in FIG. 2.
- FIGS. 6A to6E are views showing other shapes which can be employed in the punching of the discs to form the slit apertures.
- FIG. 7 is a schematic elevation view showing a plate used over an existing underdrain system to provide advantages of the invention.
- In the drawings, FIG. 1 shows in perspective major components of a
liquid filtration system 10 partially in accordance with prior art and also in accordance with features of the invention to be described below. The filtration system is formed as part of a tank typically of concrete and having afloor 12. This is a system of the type described in U.S. Pat. No. 4,331,542, as well as some of the other patents referenced above. The filtration system, as described above and also in the '542 patent, has a bed ofgranular material 14 which may be topped with a layer ofbituminous material 16. Supporting thegranular bed 14 is aperforated surface 18 at the bottom of the tank, preferably a corrugated surface as shown and as described in the '542 patent. Such a surface preferably is formed of a series of perforatedlongitudinal ribs 20 which form triangular or trapezoidal cross-sectional shapes when placed against thefloor 12. - In a preferred embodiment, as shown particularly in FIG. 5, each perforated
longitudinal rib 20 preferably has ahorizontal flange 22 at left and right extremities, these flanges of adjacent longitudinal ribs being slightly spaced apart in the completed underdrainunit 24, thus defining troughs of the corrugations which are partly constituted by thetank floor 12 itself. As explained in U.S. Pat. No. 4,331,542, the longitudinal ribs define inner spaces orchambers 26 which collect liquid filtrate passing through thegranular bed 14 and through the multiplicity ofperforations 28 in the ribs. This filtrate travels to and collects in a gutter orgullet 30 of the tank bottom. - As noted above, granular filtration systems and underdrain units of this general type are ordinarily equipped with liquid backwashing subsystems, and also pressurized air (or gas), sometimes called scouring air, which is delivered adjacent to the underdrain perforations and to the backwashing liquid to aid in the backwashing of debris from the filter bed. FIG. 5 shows a form of air scour subsystem wherein air is distributed through a tubular
structural member 30 which has air distribution outlet holes or slits shown at 32. This tubularstructural member 30 also serves to retain the underdrainstructures 20 down against thetank floor 35, thus serving a dual purpose, as disclosed in the above referenced application Ser. No. 09/170,870, U.S. Pat. No. 6,090,284. - FIG. 2 shows in flat plan view a sheet of
metal 38, preferably stainless steel in a thickness of about 1.6 mm or slightly under {fraction (1/16)}″, from which the perforations orapertures 28 are formed in accordance with the invention. FIGS. 2 and 3 show that in one embodiment, the apertures are formed by a stamping process, as by a punch press which stamps or punches out raiseddiscs 40 from the flat sheet ofmaterial 38. The raiseddiscs 40 formed in accordance with this embodiment are generally circular, with diameters which may be approximately ⅜″ to 1″. The discs are punched to a controlled depth which opensslits 42 between the disc and the surrounding flat field of metal, and these slits are highly consistent in width. A preferred width for this embodiment is about 0.010″. - The
discs 40 are stably and rigidly retained on theflat metal sheet 38 bymetal bridges 44 which are left remaining in the stamping process. The stamping die is shaped so as to leave thesemetal bridges 44 and is precisely formed to result in highly consistently-sized slits 42 serving as perforations for passage of filtrate. With the consistently formed openings in sizes of about 0.010″ as is preferred for some applications, thegranular material 14 can have sand piled directly on the underdrain structure formed from thesheet metal plate 38, and an intermediate bed of gravel in gradation of sizes can be eliminated. This can save up to about one foot of space in some types of filtration systems. - The metal stamping, a portion of which is shown in FIG. 2, is formed into an underdrain structure which preferably is trapezoidally shaped as shown in FIG. 5. The bending of the stamped metal, along
bend lines - FIGS. 2 and 3 show stampings which form raised
discs 40 connected by two opposed metal bridges 44. However, as discussed above, these bridges can be greater in number, such as three or four around a circuit of slits, so as to assure a more secure, rigid and stable connection between the raised discs and the surrounding flat metal area. Thus, in another preferred embodiment three equally spaced bridges are left remaining from the stamping process, thus providing three arcuate slits which are spaced apart 120° and which are separated by the bridges. FIG. 4 shows an embodiment wherein raiseddiscs 40 are retained to the surroundingmetal plate 38 with four such metal bridges 44. Thus, four arcuate slits or punchedslots 42 are formed as filtrate apertures, separated by thebridges 44. However, three such bridges are generally sufficient. - Although FIGS. 2, 3 and4 show aperture slits 42 in a circular pattern, with circular raised
discs 40 formed in the stamping process, the circuit of slits and the shape of the disc need not be circular. It is sufficient that the slits be arranged in some form of circuit, the slits being separated by bridges, such that a raised disc of any practical shape is formed in the punching or stamping operation. A circle is an efficient shape, but FIGS. 6A-6E shows other shapes, as examples, which can be employed. FIG. 6A shows schematically a series of sixslits 42 a in a hexagonal pattern, with bridges 44 a between adjacent slits. Thus, a hexagonal raised disc 40 a is formed. FIG. 6B shows a square raised disc 40 b, with a pattern of four slits 42 b in a square arrangement, and this could be a non-square, rectangular arrangement. - FIGS. 6C, 6D and6E show other shapes, including a triangular raised
disc 40 c, with threeslits 42 c in a triangular pattern; an octagonal arrangement in FIG. 6D, with an octagonal raiseddisc 40 d; and an oval or elliptical shape in FIG. 6E, with a pair ofslit apertures 42 e defined between the surrounding flat metal and a raisedoval disc 40 e. Only twoslits 42 e are shown at FIG. 6E, but there could be three or four slits. - FIG. 7 shows schematically another application for the punched slot openings formed in accordance with the invention. The drawing shows existing
underdrain structures 20 a as implemented prior to the invention, and these typically have {fraction (3/16)}″ diameter holes for the filtrate. As noted above, these require a support gravel system above the underdrain structure, for supporting the fine granule filter medium such as sand. These existing underdrain systems can be fitted with aflat plate 52 placed across the tops of and supported by the flat top portions 20 b of the existing underdrain plates orstructures 20 a. This eliminates the need for a support gravel bed above the underdrain structures, increasing the vertical height available for the actual filter medium by about 12″, and thus improving the filtering capability of the existing filter. - The
plate 52 has punched openings as described above (not shown in FIG. 7). By leaving the existingunderdrain structure 20 a in place, the illustrated arrangement makes this filter improvement very inexpensive. Theflat plates 52 can be attached toside walls 54 of the filter system via anangled bend 55 in the plate, with stainless steel anchors 56 as shown, and attached to the tops of the existingunderdrain structures 20 a with stainless steel machine screws indicated at 58. Other methods of securing can be used. Filter sand or anthracite can be placed directly on top of theflat plates 52 with their very fine, preferably 0.010″ punched openings. Because theplates 52 lie flat, they need to be somewhat thicker than the folded plates forming the underdrainstructures 20 described above, in order to support the filter medium and withstand the forces generated by a high rate backwash without permanent deforming. - The above described preferred embodiments are intended to illustrate the principles of the invention, but not to limit its scope. Other embodiments and variations to this preferred embodiment will be apparent to those skilled in the art and may be made without departing from the spirit and scope of the invention as defined in the following claims.
Claims (11)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10/185,638 US6691413B2 (en) | 2000-11-02 | 2002-06-28 | Underdrain filtration system with stamped perforations |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/705,458 US6569328B1 (en) | 2000-11-02 | 2000-11-02 | Underdrain filtration system with stamped perforations |
US10/185,638 US6691413B2 (en) | 2000-11-02 | 2002-06-28 | Underdrain filtration system with stamped perforations |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/705,458 Division US6569328B1 (en) | 2000-11-02 | 2000-11-02 | Underdrain filtration system with stamped perforations |
Publications (2)
Publication Number | Publication Date |
---|---|
US20020166807A1 true US20020166807A1 (en) | 2002-11-14 |
US6691413B2 US6691413B2 (en) | 2004-02-17 |
Family
ID=24833537
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/705,458 Expired - Lifetime US6569328B1 (en) | 2000-11-02 | 2000-11-02 | Underdrain filtration system with stamped perforations |
US10/185,638 Expired - Lifetime US6691413B2 (en) | 2000-11-02 | 2002-06-28 | Underdrain filtration system with stamped perforations |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/705,458 Expired - Lifetime US6569328B1 (en) | 2000-11-02 | 2000-11-02 | Underdrain filtration system with stamped perforations |
Country Status (1)
Country | Link |
---|---|
US (2) | US6569328B1 (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20050154788A1 (en) * | 2001-11-26 | 2005-07-14 | Microsoft Corporation | Methods and systems for adaptive delivery of multimedia contents |
WO2007096837A2 (en) * | 2006-02-23 | 2007-08-30 | Siobhan Sandra Beauchamp | A water filter and a water collector |
US20110073549A1 (en) * | 2009-09-30 | 2011-03-31 | Itt Water & Wastewater Leopold, Inc. | Clog Resistant Media Retainer Assembly |
WO2014134468A1 (en) * | 2013-03-01 | 2014-09-04 | Graver Technologies, Llc | Underdrain filter for power generation and liquid process filtration vessels and method of using the same |
Families Citing this family (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6569328B1 (en) * | 2000-11-02 | 2003-05-27 | Gary D. Haggard | Underdrain filtration system with stamped perforations |
US7090771B2 (en) * | 2002-06-18 | 2006-08-15 | Infilco Degremont, Inc. | Filtration system underdrain |
US6921481B2 (en) * | 2002-06-18 | 2005-07-26 | Ondeo Degremont, Inc. | Automatic backwash filter system |
US6830684B2 (en) * | 2002-07-10 | 2004-12-14 | U.S. Filter Corporation | Integrated liquid and gas distribution device for underdrain block laterals |
US7446352B2 (en) * | 2006-03-09 | 2008-11-04 | Tela Innovations, Inc. | Dynamic array architecture |
US8491787B2 (en) * | 2011-06-09 | 2013-07-23 | Johnson Screens, Inc. | Leveling hold-down mechanism for lateral screens |
US8871093B2 (en) | 2012-01-12 | 2014-10-28 | Xylem Water Solutions Zelienople Llc | Filter media retainer assembly |
US10143944B2 (en) | 2016-05-04 | 2018-12-04 | Ovivo Inc. | Filter underdrain with internal air scour laterals |
US10793351B2 (en) | 2018-12-21 | 2020-10-06 | Curbtender, Inc. | Leaf collection vehicle |
US10941050B2 (en) | 2019-03-15 | 2021-03-09 | Westech Engineering, Inc. | Modular underdrain systems |
CN113694587B (en) * | 2021-09-20 | 2022-12-20 | 上海水天一线环境科技有限公司 | Black and odorous water body foreign matter separator |
Family Cites Families (29)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1304493A (en) * | 1919-05-20 | Method op forming separators for wells | ||
US947217A (en) * | 1909-01-19 | 1910-01-18 | Vermont Farm Machine Company | Subdivider for the bowls of centrifugal liquid-separators. |
US1028066A (en) * | 1909-04-13 | 1912-05-28 | Smith Metal Perforating Company | Process for making well-casing. |
US1055675A (en) * | 1912-03-26 | 1913-03-11 | Smith Metal Perforating Company | Process of making plates for well and drainage casings. |
US2781097A (en) * | 1951-08-07 | 1957-02-12 | Extraction & Chemical Company | Manufacturing small-hole sieves |
US2861326A (en) * | 1954-02-01 | 1958-11-25 | Drill Dev Company | Method of making punch plate screens |
US3511072A (en) * | 1965-10-24 | 1970-05-12 | Borg Warner | Sheet metal punch |
DE1536824C3 (en) * | 1967-05-05 | 1975-08-07 | Waldemar Hoening Ohg, 4401 Sendenhorst | Process for producing multi-layer filter disks from wire mesh, perforated metal sheets or the like |
DE1961417A1 (en) * | 1969-12-08 | 1971-06-16 | Hoesch & Soehne Eberhard | Perforated filter plate with grooved sur- - faces |
US3762559A (en) * | 1972-07-17 | 1973-10-02 | Rostone Corp | Filter bottom and molded module therefor |
DE2352177C3 (en) * | 1973-10-17 | 1983-12-29 | Výzkumný ústav chemických zařízení Brno, Brno-Královo Pole | Sieve tray for mass transfer columns |
DE2538239C3 (en) * | 1975-08-28 | 1978-08-17 | L. Schuler Gmbh, 7320 Goeppingen | Device for conveying punched parts |
US4331542A (en) * | 1980-08-01 | 1982-05-25 | Enviroquip, Inc. | Underdrain unit with air/water backwash for granular filtration system |
US4659462A (en) | 1984-04-30 | 1987-04-21 | CH2 M Hill, Inc. | Apparatus for pretreatment of water using a bed of granular activated carbon |
US4707257A (en) | 1986-05-29 | 1987-11-17 | The Graver Company | Air/water distributor underdrain |
US4932112A (en) * | 1988-10-06 | 1990-06-12 | Tim Tikkanen | Sieve plate and process for making it |
US5019259A (en) * | 1989-06-15 | 1991-05-28 | Hambley John B | Filter underdrain apparatus with partitioned distributor conduits |
US5015383A (en) | 1989-06-15 | 1991-05-14 | Johnson Filtration Systems Inc. | Slotted screen scallops for high loading pressures and method of making same |
US5269920A (en) | 1991-04-03 | 1993-12-14 | The F. B. Leopold Co., Inc. | Cap system for underdrains in gravity filters |
US5156738A (en) | 1991-06-21 | 1992-10-20 | Johnson Filtration Systems Inc. | Apparatus for uniformly distributing gas and/or liquid in an underdrain lateral system |
US5332497A (en) | 1991-10-25 | 1994-07-26 | Baker Hughes Incorporated | Nozzleless underdrain for granular filtration system |
US5160614A (en) | 1992-02-25 | 1992-11-03 | The F.B. Leopold Company, Inc. | Air duct block for air/water underdrain systems in gravity filters |
JPH06170117A (en) | 1992-08-05 | 1994-06-21 | Peter J Neuspiel | Underlying water collecting module and system for filtering device |
US5292437A (en) * | 1992-09-21 | 1994-03-08 | Bunn-O-Matic Corporation | Multilayer frustoconical filter structure |
FR2705583B1 (en) | 1993-05-28 | 1995-08-18 | Degremont | Improvements made to filtering devices for clarifying liquids, especially water. |
US5489388A (en) | 1994-04-12 | 1996-02-06 | The F. B. Leopold Co., Inc. | Apparatus and method for improving gas backwash in lateral underdrains |
FR2759720B1 (en) * | 1997-02-19 | 1999-04-30 | Degremont | PROCESS FOR PRODUCING A FILTER FLOOR FOR WATER TREATMENT |
US6090284A (en) * | 1998-10-13 | 2000-07-18 | Enviroquip, Inc. | Underdrain unit for granular filtration system |
US6569328B1 (en) * | 2000-11-02 | 2003-05-27 | Gary D. Haggard | Underdrain filtration system with stamped perforations |
-
2000
- 2000-11-02 US US09/705,458 patent/US6569328B1/en not_active Expired - Lifetime
-
2002
- 2002-06-28 US US10/185,638 patent/US6691413B2/en not_active Expired - Lifetime
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20050154788A1 (en) * | 2001-11-26 | 2005-07-14 | Microsoft Corporation | Methods and systems for adaptive delivery of multimedia contents |
WO2007096837A2 (en) * | 2006-02-23 | 2007-08-30 | Siobhan Sandra Beauchamp | A water filter and a water collector |
WO2007096837A3 (en) * | 2006-02-23 | 2007-11-15 | Siobhan Sandra Beauchamp | A water filter and a water collector |
US20110073549A1 (en) * | 2009-09-30 | 2011-03-31 | Itt Water & Wastewater Leopold, Inc. | Clog Resistant Media Retainer Assembly |
US8657122B2 (en) | 2009-09-30 | 2014-02-25 | Xylem Water Solutions Zelienople Llc | Clog resistant media retainer assembly |
WO2014134468A1 (en) * | 2013-03-01 | 2014-09-04 | Graver Technologies, Llc | Underdrain filter for power generation and liquid process filtration vessels and method of using the same |
Also Published As
Publication number | Publication date |
---|---|
US6691413B2 (en) | 2004-02-17 |
US6569328B1 (en) | 2003-05-27 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US6569328B1 (en) | Underdrain filtration system with stamped perforations | |
EP0900114B1 (en) | Fluid treatment media support system | |
US7138056B2 (en) | Filter underdrain system for backwash flow and method for measuring same | |
US5976370A (en) | Underdrain structure for media filters | |
US7410578B2 (en) | Underdrain apparatus and method of manufacturing same | |
US7063787B2 (en) | Filter media retaining cap and hold down grid | |
US6190568B1 (en) | Method for retrofitting a false bottom underdrain filter system | |
JPH03114502A (en) | Strainer assembly | |
JP4299396B2 (en) | Air-water distribution device and water treatment device using the air-water distribution device | |
JP3338948B2 (en) | Filtration tank for water treatment using porous holder | |
WO2002085487A1 (en) | Device and method for filtering a liquid | |
AU2018268843B2 (en) | Self-cleaning, groutless, filter underdrain | |
JPS60244310A (en) | Filter apparatus | |
CA2543681C (en) | Filter underdrain system for backwash flow and method for measuring same | |
JP3741698B2 (en) | Enbico type lower water collector | |
KR101081522B1 (en) | Support Structure of Perporated Block for Underdrain | |
JPH0233846Y2 (en) | ||
CA2170231A1 (en) | Filtration media retention device | |
MXPA98008837A (en) | Flui treatment media support system | |
GB2074037A (en) | Upflow liquid filter | |
JPH06198276A (en) | Air distribution device for active carbon adsorption equipment |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
STCF | Information on status: patent grant |
Free format text: PATENTED CASE |
|
FEPP | Fee payment procedure |
Free format text: PAT HOLDER NO LONGER CLAIMS SMALL ENTITY STATUS, ENTITY STATUS SET TO UNDISCOUNTED (ORIGINAL EVENT CODE: STOL); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY |
|
AS | Assignment |
Owner name: EIMCO WATER TECHNOLOGIES, LLC, UTAH Free format text: MERGER;ASSIGNOR:ENVIROQUIP, INC.;REEL/FRAME:018109/0531 Effective date: 20060811 |
|
FPAY | Fee payment |
Year of fee payment: 4 |
|
AS | Assignment |
Owner name: GLV FINANCE HUNGARY KFT., ACTING THROUGH ITS LUXEM Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:EIMCO WATER TECHNOLOGIES, LLC;REEL/FRAME:025380/0938 Effective date: 20090401 |
|
FPAY | Fee payment |
Year of fee payment: 8 |
|
SULP | Surcharge for late payment |
Year of fee payment: 7 |
|
AS | Assignment |
Owner name: OVIVO LUXEMBOURG S.A.R.L., LUXEMBOURG Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:GLV FINANCE HUNGARY KFT, ACTING THROUGH ITS LUXEMBOURG BRANCH;REEL/FRAME:028732/0453 Effective date: 20110513 |
|
FPAY | Fee payment |
Year of fee payment: 12 |
|
AS | Assignment |
Owner name: OVIVO FINANCE INC., CANADA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:OVIVO LUXEMBOURG S.A.R.L.;REEL/FRAME:037874/0935 Effective date: 20150101 |
|
AS | Assignment |
Owner name: OVIVO INC., CANADA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:OVIVO FINANCE INC.;REEL/FRAME:037979/0362 Effective date: 20150101 |